The purpose of the proposed studies is to characterize the differences between normal and diseased hearts in terms of mechanical features of their contraction. The immediate aims are focused on three major areas: The first is to identify the performance features of diseased canine hearts in terms of global parameters of end-systolic pressure (P)-volume (V) relationship such as E max' Vd and T max' which we have determined in normal hearts over years. The diseased hearts to be studied include concentrically hypertrophied left and right ventricles by chronic pressure overloading, dilated ventricles by volume overloading, and acute global ischemia. As associated problems, P-V relationship of ejecting left and right atria will be determined. The correlation between the P-V area and ventricular O2 consumption will also be explored because of our preliminary finding that the former could predict the latter extremely well. The second aim is to develop a new method to measure instantaneous shape, lumen volume, wall thickness and regional shortening of the left and right ventricles in closed-chest dogs. We believe such a measurement can be done by implanting multiple markers in the endocardial and or epicardial layers, taking high-speed bi-plane cine-ventriculogram and reducing the markers' images into the knowledge of their positions in space. This method is currently being developed by the support of another research grant (HL24357) and will open the way to knowing the P-V relation parameters of in situ ventricles and regional stress-strain relation (e.g., finite element analysis).